Cryo-EM structure of the bacteriophage T4 isometric head at 3.3-Å resolution and its relevance to the assembly of icosahedral viruses.

The 3.3-Å cryo-EM structure of the 860-Å-diameter isometric mutant bacteriophage T4 capsid has been determined. WT T4 has a prolate capsid characterized by triangulation numbers (T numbers) T = 13 for end caps and T = 20 for midsection.

Glycosylation and oligomeric state of envelope protein might influence HIV-1 virion capture by α4β7 integrin.

The α4ß7 integrin present on host cells recognizes the V1V2 domain of the HIV-1 envelope protein. This interaction might be involved in virus transmission. Administration of α4ß7-specific antibodies inhibit acquisition of SIV in a macaque challenge model.

Cryo-EM structure of the bacteriophage T4 portal protein assembly at near-atomic resolution.

The structure and assembly of bacteriophage T4 has been extensively studied. However, the detailed structure of the portal protein remained unknown. Here we report the structure of the bacteriophage T4 portal assembly, gene product 20 (gp20), determined by cryo-electron microscopy (cryo-EM) to 3.

Structure-function analysis of the DNA translocating portal of the bacteriophage T4 packaging machine.

Tailed bacteriophages and herpesviruses consist of a structurally well conserved dodecameric portal at a special 5-fold vertex of the capsid. The portal plays critical roles in head assembly, genome packaging, neck/tail attachment, and genome ejection. Although the structures of portals from phages φ29, SPP1, and P22 have been determined, their mechanistic roles have not been well understood.

Portal-large terminase interactions of the bacteriophage T4 DNA packaging machine implicate a molecular lever mechanism for coupling ATPase to DNA translocation.

DNA packaging by double-stranded DNA bacteriophages and herpesviruses is driven by a powerful molecular machine assembled at the portal vertex of the empty prohead. The phage T4 packaging machine consists of three components: dodecameric portal (gp20), pentameric large terminase motor (gp17), and 11- or 12-meric small terminase (gp16). These components dynamically interact and orchestrate a complex series of reactions to produce a DNA-filled head containing one viral genome per head.